Method of manufacturing multi-layer game ball

ABSTRACT

A process for producing multi-layer game ball products includes the steps of extruding an inner layer precursor as a parison in a partial melt state, forming an outer layer, introducing the inner and outer layers into a mold and expanding the parison within the mold to form the multi-layer game ball product. The outer layer may take the form of pre-cut panels vacuum supported in the mold and an intermediate layer may be provided for dimensional stability in the product. Subsequent to expanding the parison a filler such as foam may be injected into the center space for forming a core.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of application Ser. No. 08/831,584,filed Apr. 9, 1997 now U.S. Pat. No. 6,261,400.

BACKGROUND OF THE INVENTION

This invention relates to the field of game balls. More specifically,this invention relates to a multi-layered game ball product and aprocess for the manufacture thereof.

Efficient manufacturing processes for game ball products having a singlelayer are well known. The game ball product can be a finished game ballor form the core of a finished game ball. Game ball products produced ofa single layer of a material can display less than optimalcharacteristics. The material of the single layer typically must becapable of performing several different functions simultaneously. Forexample, a single layer basketball must be constructed of a materialthat can form an air-tight bladder. In addition, the same material mustprovide abrasion resistance for an adequate product life for the gameball product. Furthermore, the same material must have dimensionalstability for the game ball product to resist overexpansion as the ballis inflated and is used during the product lifetime. Single layermaterials typically cannot provide optimal characteristics for all theperformance requirements.

Given these differing operational requirements and deficiencies of asingle layer game ball product, it is well known to produce a game ballproduct having multiple layers of differing materials. Each layer of themulti-layer game ball product is directed to providing a specificfunction or characteristic for a given performance requirement. Forexample, a game ball product may be produced of two layers. The outerlayer provides abrasion resistance, and the inner layer, such as abladder, provides an air-tight seal for the game ball product.Multi-layer game ball products therefore typically have superiorperformance characteristics relative to single layer game ball products.However, multi-layered game ball products typically require additionalmanufacturing steps compared to the production of the single layeredgame ball product. Therefore, multiple layered game ball productstypically have a higher relative production cost and a more extendedproduction time.

For example, basketballs are conventionally constructed by cold moldingor hand laying panels of rubber, leather or synthetic leather onto abasketball carcass. These multi-layer basketballs typically requireadditional manufacturing steps in comparison to a single layer game ballproduct.

Single and multi-layer game ball products are also used as game ballcores. Game ball products employed as game ball cores for baseballs andsoftballs are known to be manufactured of flexible, semi-rigid and rigidpolyurethane foam, rotational molded polyolefins, foamed ionomers, cork,kapok and wound string. These conventional game ball cores typicallyrequire multiple manufacturing steps in addition to furthermanufacturing to apply an outer shell to the core. Each additionalmanufacturing step typically increases final cost of the finished gameball.

SUMMARY OF THE INVENTION

Briefly stated, the invention is for the process of manufacturing amulti-layered game ball product wherein at least the inner layer isformed by a molding process. More specifically, the invention is for theprocess of manufacturing a multi-layered game ball product by formingthe game ball product within a mold wherein at least the inner layer ofthe game ball product is formed by the blow molding of a parison.

The process of the invention is for forming a game ball product havingan inner and an outer layer. A parison is formed of at least the innerlayer. The outer layer is formed. The inner and outer layers areintroduced into a mold. The parison is then expanded to form amulti-layer game ball product.

The process of the invention allows for production of multi-layer gameball products by a reduced number of manufacturing steps relative to thenumber of manufacturing steps required for conventional processes tomanufacture multi-layered game ball products. The process of theinvention employs blow molding to manufacture a multi-layered game ballproduct. The inner layer of the game ball is preferably extruded in apartial melt state to form a parison. The parison can also have 1-5additional co-extruded layers, each layer preferably chosen to optimizea particular performance requirement of the final game ball product.Pressurized gas is then introduced into the parison to expand theparison against the mold to form the game ball product. After the gameball product has sufficiently cooled, the game ball product is removedfrom the mold.

In one preferred embodiment of the process, a co-extruded three layerparison is blow molded to form a finished game ball. The material of theouter layer is selected for feel and abrasion resistance. The materialof the intermediate layer is selected for dimensional stability when thegame ball product is inflated and the material of the inner layer isselected for air entrapment. The parison of the three layers is blowmolded to form the finished game ball product.

In a further embodiment of the invention, particularly suited for themanufacture of basketballs, an inner layer can be blow molded ontopre-cut panels supported on the inside surface of a mold to produce amulti-layered game ball product. For example, a multi-layered basketballcan be produced by vacuum supporting outer layer panels of syntheticleather on the inside of a basketball mold. The inner layer of thebasketball is extruded in a partial melt state as a parison into themold and blow molded onto the outer layer panels. The parison in thepartial melt state bonds to the synthetic leather panels to form thefinished multi-layer basketball. As an alternative, an adhesive can beapplied to the outer layer panels prior to the blow molding to providebonding between the inner layer and the outer layer panels.

In still another embodiment of the invention, the multi-layered gameball product can be injected with a filler subsequent to blow molding ofthe parison. For example, a softball can be produced by blow molding amulti-layer parison onto a softball mold to form a game ball shell. Theresulting game ball shell is then filled with a foam to complete thefinished game ball.

In addition, the filled game ball product manufactured by the process ofthe invention can be employed as the core for a finished game ball. Anadditional outer layer can be molded onto the filled game ball product.Alternately, a conventional softball or baseball cover can also bestitched onto the filled game ball product to form the finished gameball.

An object of the invention is to provide a production process for theefficient manufacture of a multi-layered game ball product.

Another object of the invention is to provide a production process tomanufacture a multi-layered game ball product with a reduced number ofproduction steps relative to a conventional multi-layer game ballproduct process of manufacture.

A further object of the invention is to provide a production processhaving an increased production rate of game ball products.

A still further object of the invention is to provide a game ballproduction process having reduced costs relative to conventionalproduction processes of multi-layer game ball products.

These and other objects of the invention will be apparent from thefollowing description and figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a game ball product manufactured bythe process of the invention;

FIG. 2 is a cross-sectional view of an alternate game ball productmanufactured by the process of the invention;

FIG. 3 is a schematic, cross-sectional side view of a blow moldingapparatus and parison employed in the process of the invention;

FIG. 4 is a schematic, cross-sectional side view of a blow moldingapparatus and parison for production of a panelled game ball product bythe process of the invention;

FIG. 5 is a fragmentary, enlarged cross-sectional view of a game ballproduced from the apparatus of FIG. 4; and

FIG. 6 is a schematic, cross-sectional side view of a blow moldingapparatus and parison for production of an alternate embodiment of thepanelled game ball product produced by the process of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the drawings wherein like reference numerals representlike components throughout the figures, a multi-layer game ball productproduced in accordance with the process of the invention is designatedby the numeral 10. The game ball product 10 has at least an inner layer12 and an outer layer 14. (See FIG. 1) Interposed between the innerlayer 12 and outer layer 14 can be at least one intermediate layer 16.At least the inner layer 12 is blow molded to form the multi-layer gameball product 10. The game ball product 10 can be a finished game ball ora game ball core requiring additional manufacturing steps to becompleted.

The game ball product 10 is manufactured by a blow molding process. (SeeFIG. 3) In the blow molding process of the invention, an extruder head20 forms or extrudes a preform or parison 22 of at least the inner layer12 in a semi-melt state. The parison is preferably extruded into a mold24. However, the parison 22 can be extruded or formed outside the mold24 and then positioned within the mold 24. The outer layer 14 can beco-extruded or co-formed with the inner layer, or the outer layer 14 canbe pre-positioned on the interior surface of the mold 24. The halves ofthe mold 24 are driven together to close the mold 24 around the parison22. The excess portions of the parison 22 extending above and below thecavity formed by the mold 24 are pinched off by the mold 24 as the moldis closed. Next a pressurized gas is introduced into the parison 22 toexpand the parison 22 within the mold 24 and form the multi-layer gameball product 10. The game ball product 10 is then cooled and removedfrom the mold 24.

In one embodiment in accordance with the invention, the parison 22 iscomposed of 2-6 co-extruded coaxial layers of material. A co-extrudedparison 22 has each layer in a semi-melt state and each layer isgenerally in surface to surface contact with each adjacent layer. Forthe manufacture, for example, of a basketball, the parison 22 preferablyhas two or three layers. The material for the outer layer 14 for eitherthe two or three layer basketball is selected for “feel” and abrasionresistance. The outer layer 14 is preferably a low durometer materialsuch as styrene-butadiene-styrene block copolymer, for example Kraton™marketed by Shell; a thermoplastic polyurethane; a dynamicallyvulcanized ethylene; or a propylene diene monomer/polypropylenecopolymer, for example ethylene propylene diene monomer (EPDM)/olefincopolymers such as Santroprene™ marketed by Monsanto; or Sarlink™marketed by DSM.

The material for the inner layer 12 is selected for air entrapment. Fora two layer game ball product 10 the inner layer 12 is preferablyconstructed of a suitable thermoplastic or thermoset material, forexample an impact-modified high density polyethylene, a low densitypolyethylene or a dynamically vulcanized thermoplastic rubber. Typicallythe material is vulcanized by the resin manufacturer using standardtechniques such as the addition of peroxide coupled with high shear ratemixing. A three layer game ball product preferably has an inner layer 12of a butyl rubber modified material. While the above-identified processis particularly well-suited for the manufacture of basketballs, othermulti-layered game ball products can be manufactured by the same processemploying the same or similarly identified materials.

The intermediate layer 16, when employed, provides dimensional stabilityto the three layer game ball product. The intermediate layer 16 ispreferably a stiff, dimensional stabilizing material such as animpact-modified high density polyethylene, a high density polyethylenewith fibers, or low density polyethylene. Additional intermediate layerscan be employed for bonding between the layers 12, 14, 16 when thelayers 12, 14, 16 are not compatible. For example, a layer ofethylene/vinyl acetate adhesive can be provided between a layer ofolefin and a layer of polyurethane for bonding therebetween.

An alternate embodiment game ball product 10′ manufactured in accordancewith the invention has a solid or filled central volume 26. For example,the process of the invention can be used for the manufacture ofsoftballs having a multi-layered blow molded shell and a filled centralvolume. (See FIG. 2) The filled game ball product 10′ can be composed of1-3 layers, but is preferably constructed of two layers and a filledcentral volume. The game ball product 10′ has a low durometer outerlayer 14 of preferably 40-80 Shore A (ASTM D2240). An example includesan EPDM/olefin-type material such as Sarlink™, marketed by DSM, having adurometer of 70-80 Shore A (ASTM D2240). The game ball further has astiffer harder inner layer 12 of preferably a material having adurometer of 40-70 Shore D (ASTM D2240).

The inner and outer layers 12, 14 are preferably co-formed orco-extruded to form a multi-layer parison 22 and blow molded inpreferably an aluminum casting or mold 24 of a soft ball. The inner andouter layers 12, 14 form a shell 11 having a central volume that isinjected with a filler 26, preferably a foam, after the blow molding iscompleted. Examples of fillers 26 include foams such as polyurea,polyurethane and syntactic foam injected into the shell 11. Preferably aliquid polyurethane mixture is introduced through the blow hole in theshell 11 by the use of a high pressure polyurethane machine. Thepolyurethane reacts and foams in situ displacing the air in the shell 11and forming the inner portion or filler 26 of the game ball product 10′.

A filled game ball product 10′ in accordance with the invention can alsobe used as a game ball core. Inner and outer layers 12, 14 of the gameball product 10′ can be composed of high density polyethylene and lowdensity polyethylene as well as EPDM/olefin materials. In oneembodiment, the shell 11 is formed of six layers. Further fillers 26 arebe employed in the shell 11 for additional strength. These fillersinclude polyurethane foams and the other above identified foams. A coveris preferably stitched over the outer layer 14 of the filled game ballproduct 10′ to form a softball or a baseball. Alternately, the cover canbe molded over the game ball product 10′.

In another alternate embodiment of a gameball product manufactured inaccordance with the invention, a multi-layered game ball product 10′″can be manufactured having a blow molded inner layer 12 and an outerlayer comprising panels 28. (See FIGS. 4 and 5) The process for themanufacture of the panelled multi-layer game ball product 10′″ isparticularly suited for the production of basketballs. Panels 28 ofleather, synthetic leather or rubber are cut from a roll of material inthe appropriate shape. The edges of the panels 28 are then preferablycut or “skived” to form bevels 30 for improved adherence or interlockingof the panels 28 to the inner layer 12. The mold may also be cut so asto allow a bevel at the insert/center carcass interface. In this case,the panels would not need to be skived, just die cut. The panels 28 arepositioned on the inside surface of a mold 24′. The mold 24′ supportsthe panels 28 by use of vacuum ports 32 holding the panels 28 againstthe interior of the mold by a vacuum force. (See FIG. 4) Alternately,the mold 24′ can be lined with a low peel strength pressure sensitiveadhesive 34 to hold the panels 28 to the mold 24′. (See FIG. 6)

The panels 28 are positioned to define channels 36 therebetween. Vents38 are located in the mold 24′ at the channels 36 to allow for airbetween the parison 22 and the panels 28 to be evacuated when theparison 22 is inflated. The parison 22 of at least the inner layer 12 isintroduced to the mold 24′ and inflated. The parison 22 preferablyadheres to the back of the panels 28 and fills the channels 36 betweenthe panels 28. (See FIG. 5) The inflated parison, still in the partialmelt state, can directly adhere to the panels 28 on the interior of themold as a result of the adhesive qualities of the blown parison 22bonding to the material of the panels 28. Alternatively, an adhesive 40can be applied to the back of the panels 28 for bonding engagement tothe inner layer 12. (See FIG. 6) Preferably at least one panel 28 isfitted with a valve 42 for the introduction of air into the final gameball product 10′″.

While preferred embodiments in accordance with the present inventionhave been illustrated and described in detail, it should be readilyappreciated that many modifications and changes thereto are within theability of those of ordinary skill in the art. Therefore, the appendedclaims are intended to cover any and all of such modifications whichfall within the true spirit and scope of the invention.

What is claimed is:
 1. A method for forming a multi-layer game ballproduct, said game ball having an inner and outer layer, the methodcomprising: co-forming a parison of at least said inner layer and saidouter layer; introducing said parison into a mold; and expanding saidparison to form said multi-layer game ball product.
 2. The method ofclaim 1 wherein said co-forming comprises co-extruding said inner andouter layers.
 3. The method of claim 1 further comprising co-forming anintermediate layer between said inner layer and said outer layer to formsaid parison.
 4. The method of claim 3 wherein said co-forming comprisesco-extruding said inner, intermediate and outer layers.
 5. The method ofclaim 3 further comprising forming an additional outer layer comprisinga plurality of game ball panels.
 6. The method of claim 5 wherein saidforming said additional outer layer comprises introducing said pluralityof game ball panels into said mold prior to expanding said parison. 7.The method of claim 1 further comprising co-forming a plurality oflayers between said inner layer and said outer layer to form saidparison.
 8. The method of claim 1 further comprising filling said gameball product with a foam.
 9. The method of claim 8 further comprisingstitching a cover over said outer layer of said game ball.
 10. Themethod of claim 9 wherein said game ball is a softball.
 11. The methodof claim 1 wherein forming said parison and introducing said parisoninto said mold are co-extensive.
 12. The method of claim 1 furthercomprising filling said game ball with a liquid.
 13. The method of claim12 wherein said game ball is a softball.
 14. The method of claim 1further comprising forming an additional outer layer comprising aplurality of game ball panels.
 15. The method of claim 14 wherein saidforming said additional outer layer comprises introducing said pluralityof game ball panels into said mold prior to expanding said parison. 16.The method of claim 15 further comprising supporting said panels in saidmold by a vacuum.
 17. The method of claim 15 further comprisingsupporting said panels in said mold by an adhesive positioned betweensaid panels and said mold.
 18. The method of claim 15 further comprisingcoating said panels with an adhesive prior to expanding said parison.